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High-accuracy aspherical mirrors and lenses with large dimensions are widely used in large telescopes and other industry fields. However, the measurement methods for large aspherical optical surfaces are not well established. Scanning deflectometry is used for measuring optical signals near flat surfaces with uncertainties on subnanometer scales. A critical issue regarding scanning deflectometry is that high-accuracy autocollimators (AC) have narrow angular measuring ranges and are not suitable for measuring surfaces with large slopes and angular changes. The goal of our study is to measure the profile of large aspherical optical surfaces with an accuracy of approximately 10 nm. We have proposed a new method to measure optical surfaces with large aspherical dimensions and large angular changes by using a scanning deflectometry method. A rotating AC was used to increase the allowable measuring range. Error analysis showed that the rotating AC reduces the accuracy of the measurements. In this study, we developed a new AC with complementary metal-oxide semiconductor (CMOS) as a light-receiving element (CMOS-type AC). The CMOS-type AC can measure wider ranges of angular changes, with a maximum range of 21 500 μrad (4500 arcsec) and a stability (standard deviation) of 0.1 μrad (0.02 arcsec). We conducted an experiment to verify the effectivity of the wide measuring range AC by the measurement of a spherical mirror with a curvature radius of 500 mm. Furthermore, we conducted an experiment to measure an aspherical optical surface (an off-axis parabolic mirror) and found an angular change of 0.07 rad (4 arcdegrees). The repeatability (average standard deviation) for ten measurements of the off-axis parabolic mirror was less than 4 nm.

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A new laser tracker using an optical frequency comb with ball lenses as a reference and targets is proposed. In this system, high-accuracy absolute length measurement based on pulsed interferometry of an optical comb is utilized. By using a ball lens with a refractive index of 2.0 as a reference, it can avoid the error caused by reference point displacement. As targets, ball lenses have a wider acceptance angle than a conventional retroreflector. In this work, two new designs of the laser tracker are proposed. The simulation and experimental investigation of the refractive index characteristics of a ball lens were examined to obtain the optimal parameters for each design. Using these designs, the one-axis absolute length measurement of as much as 10 m was performed, and its combined uncertainty was evaluated to be [(0.145 µm) 2 + (3.05 × 10 −7 l) 2 ] 1/2 , where l is measured length.